Diagnostic imaging of chronic urinary tract infections

2021-07-01 01:35 PM

On computed tomography, it is similar to the venous urogram. When no other cause is evident, cystography should be performed to look for vesicoureteral reflux.

Chronic pyelonephritis

Due to repeated recurrence of acute pyelonephritis; Continuous regurgitation in renal papillae causes gradual damage to renal parenchyma (cortex and medulla) leading to non-purulent, fibrotic interstitial nephritis, with fibrous plaques between renal cortex and calyces deformed, alternating healthy parenchymal areas.

Clinical manifestations are subacute, sometimes poor or asymptomatic until renal failure, hypertension, anemia.

Ultrasound showed small kidney, parenchymal atrophy with convex margins. The renal parenchyma is slightly hyperechoic, irrespective of the cortical medulla. Renal sinus fat deposition is common (lipomatosis).

The angiogram showed a disproportionately small kidney on the contralateral side, with convex margins, and unevenly thin parenchyma at the level of the calyx, which is club-shaped.

On computed tomography, it is similar to the venous urogram. When no other cause is evident, cystography should be performed to look for vesicoureteral reflux.

Figure: Chronic pyelonephritis.

(1. the base of the calyx is straight or convex; 2. kidney is small, the border is ridged).

Figure: Locally underdeveloped kidneys.

(1. club-shaped calyx; 2. no parenchyma).

Xanthogranulomatous pyelonephritis

Due to a silent, chronic Gram - (Proteus, E. coli) infection causing yellow tumor-like masses containing lipid-laden histiocytes. Cells replace the renal parenchyma, making the kidneys large. In principle, the disease develops after stone obstruction, with renal ischemia, pus stasis, often unilateral. If the obstruction is in the calyx, pyelonephritis is focal (10-20%), while renal obstruction is diffuse kidney damage.

Clinically atypical: cause, leukocytosis, and sometimes hip mass.

Venous urogram shows triad: large kidney, kidney stones (> 80%), excretory function decreased or lost.

Ultrasound showed large kidneys, abnormal parenchymal acoustic structure: regardless of the medulla, replaced by reduced or hollow masses, which were necrotic foci; Around the calyx of the kidney there are stones, pus stasis.

Computed tomography showed a large kidney, the renal pelvis was pulled, there were stones, and the renal sinus fat was replaced with fibrous tissue. The parenchyma is replaced by hypoechoic masses which are granulomatous granulomas (xanthoma) and hydronephrosis calyces.

Widespread perirenal and pararenal spaces, perineal muscles can be seen; can probe into adjacent organs, detect skin.

The image of gravel in the middle and surrounding cavities is a sign of bear paw prints. In a small number of patients, there is a sign of stone fracture, because the renal parenchyma grows faster than the stone, causing the stone to break and move.

The diagnosis is suggestive in the presence of a combination:

Vascular mass, yellow granules, sometimes pitted, arising from the kidney, but often infiltrating the perirenal and pararenal regions.

Kidney stones, usually coral stones

The differential diagnosis of adenocarcinoma is based on the presence of stones.

Tuberculosis of the kidney

Renal tuberculosis has a hematogenous source, usually after pulmonary tuberculosis, forming miliary tuberculosis in the kidney, which usually resolves spontaneously. In rare cases, tuberculous nodules were localized in the papillary medulla and then ulcerated into the renal calyx. The bacteria enter the urine, causing a reaction of the epithelium to form tubercles, tubercles, and ulcers, and scarring of the urinary tract, especially the junction of the renal pelvis - ureter and ureter - bladder. Extrarenal spread is rare such as perirenal abscess, perineal muscle abscess, small bowel fistula. End stage renal atrophy calcification sometimes pus.

Clinically, after the early latent stage, there is chronic cystitis, which can be associated with prostatitis, epididymitis; generally, in the setting of an associated urinary tract infection.

Urinalysis showed only white blood cells, no bacteria.

Clinical and radiographic atypicals.

Definitive diagnosis is based on direct detection of TB bacteria or urine culture.

Image analyzation.

On the unprepared abdominal radiograph, the tuberous calcification is seen at a very late stage, that is, the mastic kidney, which is rarely seen today.

Venous urogram, if taken with the correct technique, will help suggest the diagnosis with the following images:

Saw-tooth pattern along the urinary tract due to small ulcers.

Narrowing of the renal calyx, the calyx is dilated into the shape of a wine glass or a sphere, and the spines in the renal pelvis are caused by the disappearance of the calyx.

Urethral stricture in many places.

Convex shape at the base of the renal calyces due to the cavernous tubercles communicating with the renal calyces. These cavernous tubes need to be differentiated from papillary necrosis, or calyx’s diverticulum.

Small bladder.

Ultrasonography may show changes in renal sinus and renal parenchyma less suggestive.

Computed tomography can show atypical signs, dilated renal calyces, foci of decreased density in the kidney, calcifications.